Featuring rapid leg and foot movements, and made popular in the United States by the famous Riverdance company, Irish dancing has long been popular in Europe.
The 10-year-old European-based WIDA holds competitions and workshops, and certifies teachers and dancers, and is one of the many groups that help organize the thousands of Irish dancers around the world.
Kate O'Brien, 28, of Glen Mills, has been on the Saturday event's planning committee for seven months. She owns the Emerald Isle Academy of Irish Dance, and has six studios in New Jersey - Ventnor, Barrington, Bridgeton, Alloway, Egg Harbor Township, and Cape May Court House; two in Pennsylvania - West Chester and Springfield, Delaware County; and one in Newark, Del.
Philadelphia, O'Brien said, is the perfect place for WIDA to hold its first championship in the United States.
"There's a huge Irish dance presence" in the region, O'Brien said.
Of the championship-caliber dancers expected to compete in a variety of age groups on Saturday, O'Brien said that 42 are from Emerald Isle.
"It's heritage," she said of the local popularity of Irish dancing. "It's the nationality of the people in the area. It's a family affair."
Both the WIDA European and World Championships were held in April, and Maiti Clark, 15, of West Chester, was first in her age category at the Worlds in Düsseldorf, Germany.
Any American dancer could have qualified for Saturday, and participants are traveling from as far away as Florida, California, and Michigan, O'Brien said. The judges are top Irish dance experts from Ireland and Germany, and they will rank the dancers in their age groups.
O'Brien said she started Irish dancing as a teenager and in 2009 helped found the North American Irish Dance Federation.
Resch, O'Brien's student now, began at another studio when she was 7.
To stay sharp, Resch said she practices on Mondays, Tuesdays, and Wednesdays with O'Brien at three different Emerald Isle locations. Then she attends separate group practices on many Sundays and tacks on added private lessons.
"It's a lot of time," Resch said Thursday. "I've been dancing every day this week."
Still, the pressure of the competitions does not create much tension among the tight-knit family of young Irish dancers, Resch said.
"You compete against them, but they're still your friends," she said.
Nerves, however, do get bit jangled as the championship events approach.
"Very excited," Resch said of her preparation for Saturday's event. "Also, kind of nervous."